Coring Apparatus for Rubber Stator

ABSTRACT

An apparatus for removing rubber stator material from inside a housing includes a head, at least one blade, and an actuator. For example, the apparatus can be used to core out rubber material from the housing so new material can be molded therein. Also, the apparatus can be used to cut back excess rubber material newly molded in the housing. The head is rotated about an axis and is moved along the axis relative to the housing. The at least one blade is pivotably connected to the head and removes the rubber stator material at least partially from inside the housing with the rotation and movement of the head through the housing. The actuator is associated with the at least one blade and is operable to adjust a pivot of the at least one blade relative to the head.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. application Ser. No. 14/623,814, filed 17Feb. 2015, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE DISCLOSURE

A mud motor 30 as shown in FIG. 1A is used in the oil drilling industryfor directional drilling. The mud motor 30 is located on a bottom holeassembly 20 at the end of the drillstring 10 and has the drill bit 22 onits end. Inside a housing 32, the motor 30 has a rotor 40 and a stator34.

During operation, drilling fluid F pumped downhole through the drillstring 10 passes through the area between the rotor 40 and the stator34. When urged by the pressures of the flowing drilling fluid F, therotor 40 orbits inside the stator 34. A transmission shaft 24 inside themotor 30 converts the orbit of the rotor 40 to rotation of the drill bit22, from which the drilling fluid F also exits. More rotational speedcan be added to the drill bit 22 by simultaneously rotating the drillstring 10 and the rotor 40.

The rotor 40 has a number of spiraling lobes 48 along its length thatfit in complementary pockets of lobes 38 spiraling inside the stator 34of the housing 30. For example, FIG. 1B illustrates an end sectionalview of the motor housing 32 with the rotor 40 disposed inside thestator 34. Here, the rotor 40 has four lobes 48, and the stator 34 hasfive lobes 38.

To form the stator 34 for the motor 30, rubber is molded to the insidesurface of the housing 32, which is typically a tubular or section ofpipe. This process is outlined in U.S. Pat. No. 8,777,598. The moldedrubber forms a multi-lobed cavity 36. The rotor 40, which is typicallymade of stainless steel, is inserted into the stator's cavity 36, andthe rotor 40 generally has one less lobe than the stator 34. This allowsthe rotor 40 to orbit eccentrically in the stator 34 as the drillingfluid is pumped at high pressure in the cavities formed between therotor 40 and the stator 34.

Over time, the rubber of the stator 34 becomes hard and brittle due tothe high temperature environment downhole. This results in chunking andwear of the rubber seal of the stator 34 against the rotor 40.Eventually, drilling performance suffers due to wear and tear, and themotor 30 is retrieved from the hole. To rebuild the motor 30, the oldrubber must be removed, and new rubber molded in.

Other downhole devices use rotors and stators, such as disclosed above.For example, a progressive cavity pump has a helical rotor and a rubberstator and is used to pump fluids in the cavities formed as the rotor iseccentrically rotated within the stator. These devices can also becomeworn overtime and may need rubber removal and replacement.

Removing the rubber stator material from a mud motor housing or the likehas been done in various ways. For example, liquid nitrogen freezing hasbeen used to remove the rubber from the motor housing 32. To do this,the whole housing 32 is submerged in liquid Nitrogen, causing the rubberto shrink and crack. Then, the rubber is pushed out of the housing 32with a hydraulic ram. This process can be very expensive.

Burning is another technique that has been used to remove the rubberfrom the housing 32. Burning techniques are outlined in U.S. Pat. Nos.2,291,862 and 6,966,105. To do this, the housing 32 is exposed to hightemperature to effectively burn out, or break the bond of, the rubber tothe stator 34. This creates noxious smoke and fumes, and thetemperatures can damage the housing's integrity. The process is alsoslow.

A more popular form of removal uses high-pressure water blasting. Thehousing 32 is set up so that high-pressure water on the order of20,000-psi to 40,000-psi at 200 Hp can be injected into the housing 32at the rubber of the stator 34. The water blast is used to slice throughthe rubber and remove it in small chunks from the housing 32. Runoffwater from this process must be cleaned of sediment and debris,requiring an expensive filtration system. Additionally, the process isslow and expensive.

Finally, it is conceivable that the rubber stator 34 can simply bemilled, ground, or drilled out of the housing 32. As expected, theamount of debris from this would be considerable. Also, possible damagecan occur to the inner surface of the housing 32 during the process, oran excess amount of material may still remain inside the housing 32,requiring further removal steps, such as water blasting.

Regardless of how rubber is removed, the inner surface of the cleanedhousing 32 may again be molded with new rubber for a stator 34 so themotor housing 32 can be reused. During the rubber molding process torebuild the stator 34, cores are used to form the inner profile. Duringthe molding, excess rubber is typically added to the end of the housing32 to ensure that the stator 34 is formed properly.

Once the housing 32 has been formed with the rubber stator 34 inside,the excess rubber inside the housing 32 towards the ends needs to beremoved, bored to the housing's inner dimension, and chamfered with a45-deg angle or the like. Traditionally, this is done using a largeengine lathe. The motor housing 32 hangs out the end of the lathe as itis rotated, which complicates handling, and is unsafe. This processgenerally takes 30 minutes or more to complete for each end of thehousing 32 and can be very cumbersome due to the exposed rotatinghousing.

The subject matter of the present disclosure is directed to overcoming,or at least reducing the effects of, one or more of the problems setforth above.

SUMMARY OF THE DISCLOSURE

An apparatus for removing rubber stator material from inside a housingcomprises a head, at least one blade, and an actuator. The head isrotated about an axis and is moved along the axis relative to thehousing. The at least one blade is pivotably connected to the head andremoves the rubber stator material at least partially from inside thehousing with the rotation and movement of the head through the housing.The actuator is associated with the at least one blade and is operableto adjust a pivot of the at least one blade relative to the head.

In addition to the at least one blade, one or more second blades can beconnected to the head to remove the rubber stator material from insidethe housing with the rotation and movement of the head through thehousing. The one or more second blades can be fixedly connected to thehead or can be pivotably connected to the head.

At least one drive can be operable to rotate and move the head and thehousing relative to one another. For example, the drive can include afirst drive (e.g., a motor connected to a shaft and having the headcoupled thereon) operable to rotate the head. Additionally, the drivecan include a second drive (e.g., motor and cart) disposed on a trackand operable to move the first drive and the head along the track. Athird drive can be coupled to the housing and can be operable to rotatethe housing relative to the head.

During a coring operation to remove the rubber material from inside thehousing, the at least one drive pulls the head through the rubbermaterial of the housing. During a cutback operation to remove excess ofnewly molded rubber material from inside the housing, the at least onedrive can push the head through the rubber stator material of thehousing.

The actuator associated with the head can include a piston disposed onthe head and movable against the at least one blade in response to powersupplied from a source. Another embodiment can include an adjustablebiasing element or spring means, applying a force against the head, oractuator, moveable against at least one blade. During operation, theapparatus rotates the head at a rotational speed and moves the head at atraverse speed. For its part, the actuator adjusts the pivot of the atleast one blade with a force. Overall, the rotational speed, thetraverse speed, and the force are coordinated so that the rubbermaterial is preferably removed as an elongated strip from inside thehousing.

In a method of removing rubber stator material from inside a housing, ahead is rotated about an axis relative to the housing, and the head ismoved along the axis relative to the housing. The rubber stator materialis at least partially removed from inside the housing with the rotationand movement of the head through the housing by engaging at least oneblade on the head against the rubber stator material. A pivot of the atleast one blade is adjusted relative to the head. In longer housings,usually over 21 feet, the inside diameter may increase by ¼″ to ⅜″towards the middle portion, termed “belly hone,” requiring a moveable orpivoting blade or blades to follow the inside profile and remove most orall the rubber material.

The foregoing summary is not intended to summarize each potentialembodiment or every aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a mud motor having a rotor and a stator in a motorhousing.

FIG. 1B illustrates an end sectional view of the motor housing with therotor disposed inside the stator.

FIG. 2 illustrates a side view of an apparatus for coring rubber statormaterial from a motor housing.

FIG. 3A illustrates a plan view of one arrangement of the track anddrive system for the disclosed coring apparatus.

FIG. 3B illustrates a back view of the arrangement of the disclosedcoring apparatus in FIG. 3A.

FIG. 4A illustrates a partial cross-sectional view of a coring head andactuator for the disclosed apparatus disposed on an end of a drive shaft

FIG. 4B illustrates a partial cross-sectional view of another coringhead and actuator for the disclosed apparatus.

FIG. 5 illustrates an end view of the coring head.

FIG. 6 illustrates a plan view of a blade on the coring head.

FIG. 7 illustrates an isolated view of a blade for the coring head andforces applied.

FIG. 8 illustrates a side view of a sand blasting apparatus for cleaningthe interior of the motor housing.

FIG. 9 illustrates a side view of an apparatus for cutting back excessof newly formed rubber stator material from a motor housing.

FIGS. 10A-10B illustrate cross-sectional views of a cutback deviceactuator for the disclosed apparatus disposed on one end of a driveshaft.

FIGS. 11A-11B illustrate cross-sectional views of a cutback head for thedisclosed apparatus disposed on another end of the drive shaft.

FIG. 12 illustrates a schematic of operational components of thedisclosed apparatus.

DETAILED DESCRIPTION OF THE DISCLOSURE

As noted previously, conventional techniques for removing rubber of astator from a housing can be expensive and time consuming. Disclosedherein is an apparatus and technique for mechanical removal of therubber material from inside a housing, such as a rubber stator inside amud motor housing, a progressive cavity pump, or the like.

In particular, an apparatus (100/200) removes rubber stator materialfrom inside a housing 32, such as used in a downhole mud motor orprogressive cavity pump. In one embodiment (e.g., FIG. 2), the apparatus100 cores out the rubber stator material 34 from inside the housing 32when the material needs to be replaced with a new molding. In anotherembodiment (e.g., FIG. 9), the apparatus 200 cuts back an excess portionof the rubber stator material 34 from an end inside the housing 32 whennewly molded material has been formed.

In both embodiments, the apparatus 100/200 includes a head 160/260 and adrive system 110/210. The head 160/260 is rotated about an axis and ismoved along the axis relative to the housing 32. Preferably, the head160/260 is rotated and moved axially while the housing 32 remainsstationary. However, the housing 32 can be counter-rotated, which canhave benefits as discussed below. In any event, it is possible for thehousing 32 to be rotated while the head 160/260 remains stationaryand/or for the housing 32 to be moved axially while the head 160/260remains stationary. Moreover, both the housing 32 and the head 160/260can be rotated and/or moved.

The head 160/260 has one or more blades 170/270 that remove the rubberstator material 34 at least partially from inside the housing 32 withthe rotation and movement of the head 160/260 through the housing 32.Although each of the one or more blades 170/270 can have a fixedorientation on the head 160/270, at least one of the one or more blades170/270 is preferably connected to the head 160/260 with a pivotableconnection that allows the at least one blade 170/270 to pivot on thehead 160/260. Moreover, an actuator 140/240 is associated with the atleast one pivotable blade 170/270 and is operable during the removalprocess to adjust a pivot of the at least one blade 170/270 relative tothe head 160/260.

Looking in particular at FIGS. 2 through 7, the apparatus 100 is usedfor coring out the rubber stator material 34 from inside the housing 32.The apparatus 100 has a drive system 110 having a cart 112, a firstdrive 120, and a second drive 116. The first drive 120 disposed on thecart 112 rotates a shaft 124. As shown, the shaft 124 is passablethrough the housing 32 and rotates the head 160 disposed on its distalend. The second drive 116 is also disposed on the cart 112 and moves thecart 112 along a track system 118 having rails 119. As the drive 116moves the cart 112 along the rails 119, the rotating shaft 124 is movedaxially relative to the housing 32.

To core out the rubber material 34, the housing 32 is supported in-lineopposite to the drive system 110. For example, the apparatus 100 can useself-centering pipe racks (not shown) to support the housing 32. Theshaft 124 coupled to the drive system 100 is inserted all the waythrough the housing 32 with its rubber material 34 therein, and the head160 is coupled to the end of the shaft 124. In general, the head 160 hasone or more blades 170 thereon, and at least one of the blades 170 ispivotable as discussed below.

With the operation of the drives 116 and 120, the head 160 is rotatedabout the axis of the shaft 124 and is pulled along the axis through thehousing 34. During this process, the one or more blades 170 connected tothe head 160 removes the rubber stator material 34 at least partiallyfrom inside the housing 32 with the rotation and pulling of the head 160through the housing 32. The removal is controlled in part by controllinga rotational speed of the head 160 in the housing 32 and controlling atraverse speed as the head 160 is pulled through the housing 32. Inparticular, the rotational speed of the head 160 is provided by thefirst drive 120 and other components of the drive system 110. Thisrotational speed can be coordinated with the traverse speed of the head160 provided by the second drive 116 and other components of the drivesystem 110.

Additionally, the removal is controlled in part by the actuator 140associated with at least one blade 170 pivotably connected to the head160. In particular, the actuator 140, which operable to adjust the pivotof the at least one blade 170 relative to the head 160, can adjust theforce against the at least one pivotable blade 170, either furtherexpanding or retracting the blade's pivot from the head 160 relative tothe inside of the housing 32. In this way, the at least one pivotableblade 170 can be pivoted closer to the inside surface 33 of the housing32, for example, to cut the rubber material closer to the housing'sinside surface 33.

As a goal, operation of the apparatus 100 seeks to cut, slice, shear,etc. the rubber material 34 from inside the housing 32 as an elongatedstrip, which can then be pulled from the distal end of the housing 32 asthe head 160 is pulled and rotated through the housing 32 toward theproximal end. Once removed, the rubber can be recycled and added as afiller to tires, asphalt, floor coverings, etc.

The one or more blades 170 rotated and pulled along the length of thehousing 32 tends to cut the rubber material 34 in a spiral pattern sothat the cut material can be removed from the housing's surface 33 as astrip. Additionally, the one or more blades 170 rotated and pulled alongthe length of the housing 32 tends to shear the rubber material 34 fromthe housing's surface 33 and can scrap close to the surface 33.Preferably during the removal process, the one or more blades 170 cutthe rubber material 34 close to or into an adhesive layer (not shown)that is typically used between the inside surface 33 of the housing 32and the molded rubber material 34. Being able to pivot the at least onepivotable blade 170 on the head 160 allows the cutting and shearingprovided by the head 160 to be properly adjusted as needed.

The first drive 120 can be an electric or hydraulic motor coupled to theshaft 124. To control rotation and torque, a gear box 122 and othercomponents (i.e., transmission, couplings, detachment, etc.) may be usedbetween the motor's rotation and the shaft 124. Additionally, a frame(not shown) having pillow blocks, bearings, or the like can be installedon the track 118 to help support the shaft 124 cantilevered from thefirst drive 120.

As noted above, the head 160 is preferably rotated while the housing 32remains stationary. In any event, a third drive (not shown) coupled tothe housing 32 can be operable to counter rotate the housing 32 relativeto the head 160. Because the shaft 124 is quite long (e.g., as long asthe housing 32) and is cantilevered from the drive 120 into the housing32, gravity may cause the head 160 to preferentially clear more rubbermaterial 34 from along the bottom of the surface 33 inside the housing32. To counter act this, the housing 32 can be rotated in an oppositedirection, and this rotation can be coordinated with the otheroperational parameters to achieve the desired removal.

As shown in FIGS. 3A-3B, one arrangement of the drive system 110 for thedisclosed coring apparatus 100 can have dual drives 120 together on thecart 112. In this way, two housings (32) can have the rubber statormaterial (34) cored out at the same time using parallel coringcomponents (e.g., 124, 140, 160, 170, etc.).

As shown in FIG. 3A, the second drive 116 disposed on the cart 112 canbe coupled by a sprocket 117 to a chain 115 of the track system 118.Additionally, the cart 112 has wheels 114 riding in the rails 119 of thetrack system 118. Finally, the second drive 116 can be an electric orhydraulic motor and may also have a gearbox disposed on the movable cart112. During operation, the chain 115 connected to the drive 116 is usedto move the cart 112 along the track system 118 so the coring head(s)(160) can be pulled through the motor housing(s) (32). The track system118 stabilizes the apparatus 100 against the coring torque andlongitudinal forces while providing a guiding system for the coringapparatus 100. As will be appreciated with the benefit of the presentdisclosure, other arrangements can be used for the drive system 110 ofthe apparatus 100.

FIG. 4A illustrates the coring head 160 and actuator 140 for thedisclosed apparatus 100 disposed on an end of the drive shaft 124adjacent portion of the housing 32 and rubber stator material 34. Thecoring head 160 has a head body 162 that affixes to a coring body 164with a nut 166 or cap screw. The coring body 164 in turn connects to thedrive shaft 124, for example, using a drive pin arrangement (not shown)and threaded collar 126 for quick changeover due to changes in housingdiameters. Also, the coring head 160 is removed to allow insertion ofthe coring shaft 124 through the rubber stator 34 before coring canproceed as the head 160 is pulled through the housing 32 while rotating.

The head body 162 can be disc-shaped with the one or more blades 170disposed thereabout in cutaways 167. In general, the one or more blades170 can be composed of steel or other suitable material and can beoriented at an angle (e.g., of 0 to 90-deg) relative the rotational axisof the head 160. As the head 160 rotates, the one or more blades 170ride along housing's inner surface 33 and mechanically “slice” and shearthe rubber material out in long “ropes” for easy removal from theopposite direction to the head's movement.

As noted herein, at least one of the blades 170 is movable or pivotableon the head 160. During rotating, the at least one pivotable blade 170is biased outward during coring, and the geometry of the pivotable blade170 provides increased cutting force against the housing's inner surface33 as applied torque for coring increases. The pivotable blade 170swivels at its mounting point 172 to the coring head's body 162, whichallows the pivotable blade 170 to adjust and follow the housing's innersurface 33.

To further increase cutting, the coring apparatus 100 has the actuator140 for the at least one pivotable blade 170. As shown here in FIG. 4A,for example, the actuator 140 is disposed on the coring body 164. Theactuator 140 has a hydraulic or pneumatic cylinder 144 and piston 142disposed on the coring body 164 and movable against the pivotable blade170. When energized, the piston 142 provides increased cutting bladeforce from the at least one pivotable blade 170 for enhanced rubberremoval.

In particular, the piston 142 is disposed in the cylinder 144 with oneor more ports 146 exposed to the inside 125 of the drive shaft 124.O-rings can seal communication of the port 146 to the chamber betweenthe piston 142 and cylinder 144. Power (pneumatics or hydraulics)supplied through the shaft 124 can push the piston 142 in the cylinder144 axially toward the at least one pivotable blade 170 on the head 160.The piston 142 moves or has an actuator ring 148 with an angle from zeroto 90 degrees, which provides increased cutting force in response to airor fluid pressure from the cylinder 144. Pushed by the piston 142, theangled actuator ring 148 wedges against the at least one pivotable blade170, causing it to pivot outward from the rotational axis. Release ofthe power allows a spring 147 to force the piston 142 and ring 148 awayfrom the at least one pivotable blade 170.

The source of the power (spring, pneumatics, or hydraulics) for theactuator 140 can be coupled to the shaft 124 at any desirable point.Preferably, as shown in FIG. 2, a pneumatic or hydraulic swivel 134connects a line 132 from a source 130 to the shaft 124. As the shaft 124is rotated, the swivel 134 transfers the hydraulic or pneumatic pressurefrom the source 130, into the rotating coring shaft 124, and to thecutting head 160 to actuate the at least one pivotable blade 170 withthe actuator 140 (FIG. 4A). Adjacent the swivel 134, the end of theshaft 124 can have a disconnect that includes a swivel nut, a seal, anda drive feature (e.g., a steel pin or splines) to transfer torque andpressure to the coring head 160 disposed on the end of the shaft 124.This disconnect feature is advantageous due to many different pipediameters used, and affords quick changeover while allowing the head160, the shaft 124, and the actuator 140 to be in assembly form.

FIG. 4B illustrates another coring head 160 and actuator 140 for thedisclosed apparatus 100 disposed on an end of the drive shaft 124adjacent portion of the housing 32 and rubber stator material 34. Thecoring head 160 is similar to that disclosed above and has a head body162 that affixes to a coring body 164 with a nut 166 or cap screw. Thecoring body 164 in turn connects to the drive shaft 124, for example,using a drive pin arrangement and threaded collar 126.

The head body 162 has the one or more blades 170—at least one of whichis movable or pivotable on the head 160. To further increase cutting,the coring apparatus 100 has the actuator 140 for the at least onepivotable blade 170. As shown here in FIG. 4B, the actuator 140 has abiasing member or spring 145 disposed on the coring body 164 that pushesan actuator ring 148 against the pivotable blade 170 to increase thecutting blade force from the at least one pivotable blade 170 forenhanced rubber removal. The spring 145, in the form of stacked discs orthe like, installs on the coring body 164, and the head body 162 thenmounts on the coring body 164 and is held by the mounting nut 166.

The force provided by the spring 145 can be configured during assemblyof the head 160 on the end of the pipe 124 before coring at the start ofthe housing 32. For example, the spring 145 can be selected for aparticular compressive force. A threaded nut (not shown) disposed towardthe back end of the spring 145 may be adjustable along the outside ofthe coring body 164 to adjust the spring's bias. Alternatively, themounting nut 166 can be adjusted to compress the spring 145 to a desiredamount of bias.

Depending on the characteristics of the rubber material (34) to beremoved, such as its thickness, hardness, and the like, the apparatus100 of the present disclosure rotates the head 160 at a rotational speedand moves the head 160 at a traverse speed that are coordinated. Alsodepending on the characteristics, a particular number of the one or moreblades 170 can be used, their angle or orientation on the head 160 canbe set, and the pivot and force provided by the actuator 140 for the atleast one pivotable blade 170 can be coordinated with the otheroperational parameters.

As noted herein, the head 160 can have at least one pivotable blade 170.As shown in the end view of FIG. 5, for example, the head 160 can havethree pivotable blades 170 disposed in cutaways 167 of the head's body162. The blades 170 connect to the cutaways 167 at pivot points 172using pins or the like. As also shown in FIG. 5, the head body 162 canbe triangular in shape and can fit onto a key joint on the coring body164 where a fastener (not shown) can affix the head body 162 in place.

As understood herein, not all of the blades 170 need to be pivotable onthe head 160. Instead, one or more of the blades 170 can be at fixedangles on the head 160. In one particular example, the head 160 can havethree blades 170 with one of the blades being pivotable and the othertwo being fixed.

As shown in the plan view of FIG. 6, the blade 170 can be angled on thehead body 162. For example, the blade 170 can be angled at a coringangle from 0 to 90-deg relative to the axis of rotation. Additionally,as shown in the isolated view of FIG. 7, the blade 170 has a pivot point172 at one end and widens out therefrom in a triangular shape toward acutting edge 174. As shown, the cutting edge 174 can be curved and cangenerally be angled from perpendicular relative to the flat bottom edge176 of the blade 170. Due to blade geometry, a cutting forces (F)creates a moment (M), adding increased normal force (N) between cuttingblade surface (178) and pipe inside surface (33) and improving cleaningof rubber (34) from pipe wall. Finally, the tip of the blade 170 canhave a flat top or radius edge 178, which can engage against the insidesurface (33) of the housing (32).

After coring out the rubber stator material 34, the inside surface 33 ofthe housing 32 can be further cleaned to remove any remaining rubber andadhesive left. For example, FIG. 8 illustrates a side view of a sandblasting apparatus 100 for cleaning the interior of the housing 32. Asbefore, the apparatus 100 uses the drive system 110 having a cart 112, adrive 116, and a track system 118, among other components discussedpreviously. A sandblast source 180 connects to a distributor 182 on thecart 112. A pipe 184 extends from the distributor 182 and conductssandblasting material (e.g., compressed air and sand) to a nozzle 186 onits end.

During operations, the nozzle 186 and pipe 184 are initially extendedall the way through the housing 32. As sandblasting material is theconducted out of the nozzle 186 to clean the inside surface 33 of thehousing 32, the cart 112 moves by the drive 116 along the track system118. This pulls the head 186 through the housing 32 so that successivelengths of the inside surface 33 can be cleaned. This continues untilthe head 186 reaches the end of the housing 32. Although not shown, theother end of the housing 32 may connect to a collection tank or the liketo catch the expelled sand, residual rubber and adhesive, and the like.When done, the inside surface 33 of the housing 32 can be sandblasteddown to white metal for eventual reuse.

As noted previously, the excess rubber material 34 at the end of thehousing 32 after molding of a new stator in the housing 32 needs to beremoved, bored to the housing's inside surface 34, and chamfered with adesired (e.g., 45-deg) angle. To that end, additional embodimentsinclude the disclosed apparatus 200 having a rubber cutback feature.

Looking now at FIGS. 9 through 11C, the apparatus 200 for cutting backthe rubber stator material 34 from inside an end of the housing 32 isshown. The apparatus 200 is comparable to the previously discussedembodiment so that similar reference numbers are used for likecomponents, which are not necessarily described again for the sake ofbrevity.

The apparatus 200 has a drive system 210 with a cart 212, a first drive220, and a second drive 216. The first drive 220 is disposed on the cart112 and rotates a shaft 224 passable into the housing 32. The shaft 224rotates a head 260 disposed on its distal end. The second drive 216 isalso disposed on the cart 212 and moves the cart 212 along a tracksystem 218 having rails 219. As the drive 216 moves the cart 212 alongthe rails 219, the rotating shaft 224 is moved axially relative to thehousing 32.

To cut back the rubber material 34, the head 260 is coupled to the endof the shaft 224, and the head 260 is inserted into the end of thehousing 32 with its rubber material 34 therein. Then, operating thedrives 216 and 220, the head 260 is rotated about the axis and is pushedalong the axis further into the housing 34 and then pulled out of thehousing 34. During this process, one or more blades 270 connected to thehead 260 removes excess rubber stator material 34 at least partiallyfrom inside the housing 32 with the rotation and movement of the head260 through the housing 32. The removal is controlled in part bycontrolling a rotational speed of the head 260 in the housing 32 andcontrolling a traverse speed as the head 260 is moved through thehousing 32.

Additionally, at least one of the blades 270 is pivotably connected tothe head 260. In this way, the removal is controlled in part by theactuator 240 associated with the at least one pivotable blade 270. Inparticular, the actuator 240, which is operable to adjust the pivot ofthe at least one blade 270 relative to the head 260, can adjust theforce against the at least one blade 270, either further expanding orretracting the blade's pivot from the head 260 relative to the inside ofthe housing 32. In this way, the at least one blade 270 can be pivotedcloser to the inside surface 33 of the housing 32, for example, to cutthe rubber material 34 closer to the housing's inside surface 33.

Using the cutback feature, the housing 32 remains stationary while therotating cutting head 260 is inserted in the end of the housing 30,adding to increased safety for the operation. Although only one end isshown, rotating heads 260 can be inserted into both ends of the housing32 in another arrangement to simultaneously cutback excess rubbermaterial 34 at both ends of the housing 32. A section of track 218(about 10-ft) is used to provide the cutback travel into the end of thehousing 32. Typically, the travel for the cutback operation can be about36-in.

Sensors and electronic control can allow automation of the process. Forexample, an operator can set the cutback depth and then start theprocess to run automatically. The rotating head 260 can be guarded witha cover that must be in place to start the operation.

During the cutback operation, the shaft 224 on the drive system 210 ispassable into and out of the end of the motor housing 32. In this way,the head 260 with the at least one pivotable blade 270 can cut backexcess rubber material 34 of the stator inside the housing 32 and cangive the end of the material 34 a preferred angle (e.g., 45-deg.). Ingeneral, the head 260, the at least one pivotable blade 270, and theactuator 240 can be similar to those used for coring out the rubbermaterial 34. In other words, the actuator 240 can be disposed on theshaft 224 to move axially forward against the at least one pivotableblade 270 and push the at least one pivotable blade 270 outward. Thehead 260 with its at least one pivotable blade 270 can be rotated andmoved into the end of the housing 34 to cut back the material 24 and canthen be moved out of the end to further remove any remaining materialclose to the inside surface 33 of the housing 32.

Preferably, however, a different configuration is used as shown in FIG.9. As shown here, the at least one pivotable blade 270 on the head 260pivots opposite to the previous configuration, and the actuator 240applies the pivot from an opposite direction. In general, the actuator240 is disposed toward the proximal end of the shaft 224 close to thedrive system 210. When activated, the actuator 240 pulls along the axisof the shaft 224 and moves the at least one pivotable blade 270 outwardfrom the head 260.

In particular, FIGS. 10A-10B illustrate an embodiment of the actuator240 for the disclosed apparatus 200 disposed on a proximal end of thedrive shaft 224. The shaft's end has a torque input 225 for coupling tothe gear box, motor, and other components of the drive system 210. Adraw bar 250 is movable inside the bore 226 of the shaft 224 and can bedrawn axially by a draw stroke (e.g., about ¼-in to 1-in). A hydraulicor pneumatic cylinder 244 fits about the shaft 224 and has bearings 248a-b at each end. One bearing 248 a rests against a fixed shoulder 227 onthe shaft 224, such as provided by a welded ring. The other bearing 248b rests against a reaction sleeve 252 connected by a pin 254 or the liketo the draw bar 250.

Power (pneumatics or hydraulics) supplied at the inlet 246 of thecylinder 244 pushes a piston 242 inside the cylinder 244. In turn, thepiston 242 pushes against the bearing 248 b and reaction sleeve 252,causing the draw bar 250 to slide inside the shaft's bore 226. Theconnection pin 254 between the reaction sleeve 252 and the draw bar 250can move inside a slot 227 of the shaft 224. This operations moves thedraw bar 250 of the actuator 240 back, which in turn alters the pivot ofthe at least one pivotable blade (270) on the cutback head (260) asdisclosed below. When the supply of power is stopped, a spring 256inside the shaft 224 can force the draw bar 250 back to its originalposition.

FIGS. 11A-11B illustrate an embodiment of a cutback head 260 for thedisclosed apparatus 200 disposed on the distal end of the drive shaft224. The cutback head 260 has a head body 262 with one or more blades270 affixed thereto. At least one of the blades 270 is pivotable on thehead body 262 about a pivot point 272.

The head body 262 is affixed on a coring body 264 with a retaining ring266. The coring body 264 couples to the drive shaft 224 using a drivetang and threaded collar 268. A ring 257 of the actuator 240 couples tothe draw bar 250 with a nut and stud arrangement 255.

As the draw bar 250 is drawn back in the shaft 224 during activation,the ring 257 of the actuator 240 is pulled back against the at least onepivotable blade 270, causing the blade 270 to pivot outward on its pivotpoint 272 against the inside surface 33 of the housing 32. As shown, thefront edge 274 of the blade 270 can define an angle, such as 45-deg, toprovide the desired end contour of the rubber stator material 34 beingcutback. The top end 278 of the blade 270 can be flat as shown to engageinside the surface 33 of the housing 32.

Similar to those arrangements previously described, the one or moreblades 270 can be angled on the head 260 relative to the axis ofrotation. Multiple ones of the blades 270 can be pivotable, or one ormore may be fixed on head 260. Additionally, the apparatus 200 canrotate the head 260 at a rotational speed and move the head 260 at atraverse speed that is coordinated to produce the desired cutback.Moreover, the actuator 240 can adjust the pivot of the at least onefirst blade 270 with a force that can be coordinated with these otheroperations by altering the spring force or the force from the fluid(hydraulic or pneumatic) pressure.

With an understanding of the disclosed apparatus 100/200, discussionturns briefly to operational components of an embodiment of thedisclosed apparatus 300, as schematically shown in FIG. 12. Theapparatus 300 includes a control unit 380 operatively coupled to thevarious drives and power sources of the apparatus 300, including thefirst drive 320 for rotating the head 360, the second drive 316 fortraversing the head 360 (i.e., moving the cart 312), and the powersource 330 (e.g., the pneumatic or hydraulic source) for powering theblade actuator 340. If the housing 32 is to be rotated or moved duringthe process, the control unit 380 can be operatively coupled to one ormore drives 390 for rotating and/or moving the housing 32.

The control unit 380 can be a computer or process known in the art. Thecontrol unit 380 is operable with inputs from manual controls 382 and/orautomatic controls 384. As already noted, the apparatus 300 cancoordinate the operation of the drives 320, 316, 390 and the powersource 330 to achieve the desired coring depending on thecharacteristics of the rubber material (34) to be removed, such as itsthickness, hardness, and the like. Thus, some of the inputs for thecontrols 382, 384 can include information about the geometry of therubber material (34), geometry of the housing 32, hardness of the rubbermaterial (34), number of blades 370 on the head 360, number of pivotableblades on the head 360, angle of the blades 370 on the head 360, etc.Internal algorithms, tables, or other data within the control unit 380then calculate various operational parameters, such as rotational speedfor the head 360, traverse speed of the cart 312, rotational speed ofthe housing 32, traverse speed of the housing 32, force from theactuator power source 330, pivot of the pivotable blades 370, etc., tobe used.

During operations, the control unit 380 can then implement thedetermined operational parameters. Additionally, the control unit 380may use sensors 386 to detect movements of the various components andautomate operations. Such sensors 386 can include pressure sensors forthe power source 330, torque sensors for the drives 320, 316, 390,accelerometers, proximity sensors, optical sensors, etc. Inputs fromthese and other such sensors 386 can be used by the control unit 380 toadjust the operational parameters during operations.

The foregoing description of preferred and other embodiments is notintended to limit or restrict the scope or applicability of theinventive concepts conceived of by the Applicants. It will beappreciated with the benefit of the present disclosure that featuresdescribed above in accordance with any embodiment or aspect of thedisclosed subject matter can be utilized, either alone or incombination, with any other described feature, in any other embodimentor aspect of the disclosed subject matter.

In exchange for disclosing the inventive concepts contained herein, theApplicants desire all patent rights afforded by the appended claims.Therefore, it is intended that the appended claims include allmodifications and alterations to the full extent that they come withinthe scope of the following claims or the equivalents thereof.

What is claimed is:
 1. A method of removing rubber stator material frominside a housing, the method comprising: rotating at least one of a headand the housing about an axis; moving at least one of the head and thehousing along the axis; removing the rubber stator material at leastpartially from inside the housing with the rotation and the movement byengaging at least one first blade on the head against the rubber statormaterial; and adjusting a pivot of the at least one first blade relativeto the head.
 2. The method of claim 1, wherein rotating at least one ofthe head and the housing about the axis comprises rotating a shafthaving the head disposed thereon; and wherein moving at least one of thehead and the housing along the axis comprises moving the head in thehousing.
 3. The method of claim 2, wherein moving the head in thehousing comprises at least one of pushing the head with the shaft in afirst direction into an end of the housing; and pulling the head withthe shaft in a second direction out of the end of the housing.
 4. Themethod of claim 2, wherein rotating the shaft having the head disposedthereon comprises rotating the shaft about the axis with a first drive;and wherein moving the head in the housing comprises moving the firstdrive along the axis using a second drive.
 5. The method of claim 1,wherein rotating at least one of the head and the housing about the axiscomprises rotating the housing.
 6. The method of claim 1, whereinadjusting the pivot of the at least one first blade relative to the headcomprises adjusting the pivot of the at least one first blade about apivot point on the head with an actuator having a force directedrelative to the pivot point on the head.
 7. The method of claim 6,wherein adjusting the pivot of the at least one first blade about thepivot point on the head with the actuator having the force directedrelative to the pivot point on the head comprises operating the actuatorwith fluid pressure communicated in a hollow a shaft on which the headis disposed.
 8. The method of claim 7, wherein operating the actuatorwith the fluid pressure communicated in the hollow the shaft on whichthe head is disposed comprises moving a piston with the fluid pressure;and pivoting the at least one first blade with the movement of thepiston.
 9. The method of claim 6, wherein adjusting the pivot of the atleast one first blade about the pivot point on the head with theactuator having the force directed relative to the pivot point on thehead comprises moving a piston with fluid pressure, the piston disposedon a shaft having the head disposed thereon; shifting a draw bar coupledto the piston and disposed in a hollow of the shaft; and moving aportion of the draw bar at the head against the at least one firstblade.
 10. The method of claim 1, wherein adjusting the pivot of the atleast one first blade relative to the head comprises moving a pistondisposed on the head against the at least one first blade.
 11. Themethod of claim 10, wherein moving the piston disposed on the headagainst the at least one first blade comprises supplying power from asource to the piston.
 12. The method of claim 10, wherein supplying thepower from the source to the piston comprises supply fluid pressure asthe power from a hydraulic source or a pneumatic source as the source ofthe fluid pressure.
 13. The method of claim 1, wherein removing therubber stator material at least partially from inside the housing withthe rotation and the movement comprises engaging one or more secondblades on the head against the rubber stator material.
 14. The method ofclaim 13, further comprising adjusting a pivot of the one or more secondblades relative to the head.
 15. The method of claim 1, furthercomprising coordinating a rotational speed at which the head rotatesrelative to the housing, a traverse speed at which the head movesrelative to the housing, and a force at which the at least one firstblade pivots relative to the head.
 16. The method of claim 1, furthercomprising sand blasting the inside of the housing after at leastpartially removing the rubber stator material.
 17. The method of claim1, wherein removing the rubber stator material at least partially frominside the housing with the rotation and the movement comprises cuttinga continuous strip of the rubber stator material out of the housing. 18.The method of claim 1, wherein removing the rubber stator material atleast partially from inside the housing with the rotation and themovement comprises cutting back an excess portion of the rubber statormaterial in an end of the housing.
 19. A method of removing rubberstator material from inside a housing, the method comprising: rotating ahead about an axis with rotational movement of at least one drive;moving the head along the axis through the housing with translationalmovement of the at least one drive; removing the rubber stator materialat least partially from inside the housing with the rotational movementand the translational movement by engaging at least one first blade onthe head against the rubber stator material; and adjusting a pivot ofthe at least one first blade relative to the head.
 20. A method ofremoving rubber stator material from inside a housing, the methodcomprising: rotating at least one of a head and the housing about anaxis; moving at least one of the head and the housing along the axis;cutting back at least a portion of the rubber stator material frominside the end of the housing with the rotation and the movement byengaging at least one first blade on the head against the rubber statormaterial; and adjusting a pivot of the at least one first blade relativeto the head.